现今由于中国北斗、GPS 等定位技术的日趋成熟，这些技术已经广泛被运用于商业领域；但是相对于已经被大量运用的室外定位技术，我国的室内定位技术仍然处于实验室研究的层次。在各种室内定位技术中，超宽带（UWB）技术在各方面的优势较为突出。因此利用UWB技术来实现室内定位变成一种可能。本文在现有的UWB 定位系统上，在测距与定位两个方面做了相关研究工作，提高了定位系统的精度。
本文对两种测距方式进行了误差分析，得出测距误差主要来源于两个方面：
1.节点处晶振的时钟偏移会导致测距模块接收与发送信号时的响应时间出现偏差，进而影响测距的精度，
2.节点间信号传播时因空气折射率而导致的信号传播速度变化，进而影响测距的精度。结合以上两点造成测距误差的因素，推导出两种误差系数并设计了相关的测量方法与应用方法，两种误差系数分别适用于采用了高频率稳定晶振的测距模块与未采用高频率稳定晶振的测距模块。本文还设计了一种空气折射率以及一种晶振实际频率的测量方法。本文在比较了几种UWB 定位方法后，选择基于信号到达时间差（TDOA）这一定位方法进行研究，介绍了几种常见的基于TDOA 的算法后，对Fang 算法，Chan 算法，Taloy 级数算法进行了公式的推导以及MATLAB 的仿真，结合测距中误差系数的应用，得到三种算法的误差曲线图与散点图，比较三种算法的误差，挑选出三种算法中的误差最小的Chan 算法，再套用一层卡尔曼滤波，再对其进行仿真得到误差曲线与散点图，分析其误差与标准差。实验表明在定位系统中采用误差系数对距离测量进行矫正，可以提高距离测量的精度并提高相应定位系统的精度，采用卡尔曼滤波可进一步提高定位精度。在距离测量中采用误差系数进行修正的方法可应用于室外定位。关键词: 超宽带，距离测量，误差分析，定位算法
Nowadays, with the maturing positioning technologies such as China’s Beidou and GPS, those technologies have been widely adopted in business area. However, Chinese indoor positioning technologies still remain experimental level relative to those amounting outdoor positioning technologies. Among various indoor positioning technologies, Ultra Web Band (UWB) technology’s merits stand out in this area. Hence, it is potential to utilize UWB on order to achieveindoor positioning. This paper investigates into ranging and positioning functions of the current UBW positioning system with increasing the accuracy of positioning system.
This paper analyses the errors of two ranging approaches with concluding that the errors are primarily caused by the below two factors:
1. The clock skew that occurs between the nodes of crystal oscillation will cause deviation on the time of response when ranging models send and receive signals, in which the accuracy of ranging is affected.
2. The signal propagation speed changes caused by the refractive index of the air during the propagation of signals between nodes,which in turn affects the accuracy of ranging. Combining the two factors causing the ranging error,two error coefficients are derived and the related measurement methods and application methods are designed. The two error coefficients are respectively applicable to the ranging module using a high-frequency stable crystal oscillator and not using a high frequency Stable crystal ranging module. This paper also designs a method for measuring the refractive index of air and the actual frequency of a crystal oscillator.
After comparing several UWB positioning methods, this paper selects the positioning method based on the time difference of arrival (TDOA). After introducing several common algorithms based on TDOA, formula derivation and MATLAB simulation for Fang algorithm, Chan algorithm,Taloy series algorithm, combined with the application of the error coefficient in ranging, obtained the error curves and scatter plots of the three algorithms, compared the error of the three algorithms,and pick out the Chan algorithm with the smallest error among the three algorithms, and then simulated to obtain an error curve and a scatter plot, and analyze the error and standard deviation.
Experiments show that using the error coefficient to correct the distance measurement in the positioning system can improve the accuracy of the distance measurement and the accuracy of the corresponding positioning system, and the Kalman filter can further improve the positioning accuracy. The method of correcting the error coefficient in distance measurement can be applied to outdoor positioning.Key words: Ultra wide band, Distance measurement, Error analysis，Location Algorithm